title: Crystallization behavior of asymmetric PLLA/PDLA blends.
abstract: The effects of the addition of poly(D-lactide) (PDLA) on the crystallization behavior of poly(L-lactide)(PLLA) were investigated by means of differential scanning calorimetry (DSC) and temperature-dependent X-ray diffraction(XRD). When the blends were cooled from different temperatures (250, 240, and 190 °C) at the rate of cooling of 5 °C/min, stereocomplex (sc) crystallites could stay at diverse states. Accordingly, the stereocomplexes acted as a nucleation agent exerting distinct effects on PLLA crystallization. The speculated mechanisms of the stereocomplex formation and the effectiveness as a nucleating agent are schematically described. Moreover, temperature-dependent XRD was carried out to further investigate the melt-crystallization behavior of PLLA/PDLA blends in real time. Temperature-dependent XRD results indicated that even at 240 °C the stereocomplex crystallites in all blend samples existed clearly, which could not be detected by DSC. These XRD results further suggest that the onset T(c) values for the PLLA α-form crystals formation were 160, 120, 140, and 160 °C, respectively, for neat PLLA, PLLA/PDLA 95/5, 90/10, and 80/20 as well as 70/30 samples.
authors.affiliation: Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, China.
authors.forename: Jingru
authors.initials: J
authors.lastname: Sun
authors.forename: Haiyang
authors.initials: H
authors.lastname: Yu
authors.forename: Xiuli
authors.initials: X
authors.lastname: Zhuang
authors.forename: Xuesi
authors.initials: X
authors.lastname: Chen
authors.forename: Xiabin
authors.initials: X
authors.lastname: Jing
mesh_terms: D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D011091:Polyesters / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D011091:Polyesters; C033616:poly(lactide)